Aphid Density and Animal Damage to <i>Pinus patula</i> Schiede and Deppe in a Clone Bank at Melsetter Forest Research Station

Katerere, Yemi

doi:10.1080/00382167.1982.9628836

Cited by 5 publications

(5 citation statements)

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“…The result of the current study confirm my findings (Katerere, 1982) that there is no significant difference in aphid density between crown levels. The magnitude of the difference in aphid densities between crown levels was less than three aphids per 100 mm of twig length (Katerere, 1982). For this reason, it has been decided that in future E. rileyi population dynamics studies the crown will be stratified and only the mid-crown sampled.…”

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confidence: 95%

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Biology and Population Dynamics of the Pine Needle Aphid, Eulachnus rileyi (Williams) in Zimbabwe

Katerere¹

1984

South African Forestry Journal

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SYNOPSISThe biology, ecology, and population dynamics of the pine needle aphid were studied in the pine plantations of Zimbabwe. The annual cycle is simplified by the suppression of the sexual cycle, parthenogenetic reproduction occurring throughout the year. The number of nymphs produced by each adult varied from three to five a day and the total number produced from 15 to 35.Numerical change was seen to result from the action and interaction of intrinsic and extrinsic factors. The aphid numbers were observed to increase substantially between June and July, and between September and November. Exposed colonies of aphids were killed and washed off the needles by rain.Multiple regression analysis was used to try and identify factors important in aphid population fluctuations. Altitude appeared to be the most important variable influencing aphid populations, but was highly correlated to sampling date.No significant statistical differences in aphid density were found between crown levels or crown aspects. In future E. rileyi studies the crown will be stratified and only the mid-crown sampled.The pine needle aphid was found to prefer feeding on year-old and old foliage. Both young and old leaves are likely to be particularly rich in translocated nutrients.Eight species of predatory insects feeding on E. rileyi were identified. Coccinellid beetles were the most abundant predators. Hoverfly larvae, although not as abundant as the coccinellids, were found to be fairly important. The fungus E. plachoniana was found to maintain effective natural control of the aphid in two separate areas.Ants tending the aphids for their honeydew were infected by the fungus S. burmensis.

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confidence: 95%

“…Eulachnus rileyi is one of the most abundant insects in the softwood plantations in Zimbabwe (Katerere, 1983a). Being a new pest to Zimbabwe there is an urgent need to examine its biology, ecology, and population dynamics.…”

Section: Introductionmentioning

confidence: 99%

Biology and Population Dynamics of the Pine Needle Aphid, Eulachnus rileyi (Williams) in Zimbabwe

Katerere¹

1984

South African Forestry Journal

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“…In Zimbabwe, peaks of abundance of the aphid occur in July and in November (Katerere, 1984). Studies on P. patula in this country have shown that aphid densities of approximately two per 0.1 m of twig are frequently found and at this or higher densities, needles turn yellow and may be cast prematurely (Katerere, 1982).…”

Section: Introductionmentioning

confidence: 99%

Population dynamics and foraging behaviour ofDiaeretus leucopterus(Hymenoptera: Braconidae), and its potential for the biological control of pine damagingEulachnusspp. (Homoptera: Aphididae)

Murphy¹,

Völkl

1996

Bull. Entomol. Res.

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The Palaearctic pine aphids, Eulachnus agilis (Kaltenbach) and Eulachnus rileyi (Williams) have both been introduced into other continents where they have been reported causing damage to economically important pines. In Euorpe, they are attacked by the specialist parasitoid Diaeretus leucopterus (Haliday) which has been suggested as a possible biological control agent. Here we report on several aspects of the ecology of the parasitoid, conducted on E. agilis in Germany in 1993–94, to provide a more scientific basis for judging its potential for use in biological control. Parasitism of all instars in the field rarely exceeded 10% and was independent of host density. A high percentage of parasitized aphids were hyperparasitized. Measurements of the impact over 16 weeks in a greenhouse-release experiment showed that parasitism rates increased from 2 to 19% but were insufficient to suppress the aphid population below a damaging level. There was evidence of a density-dependent response. Studies on foraging behaviour showed that female parasitoids searched pines by quite extensive walks. There was no relationship between the number of aphids per tree and number of ovipositions, and the mean number of ovipositions per female per tree was 2.5 ± 0.4 eggs. The majority (55.1%) of encountered aphids did not respond to the parasitoids. However, female parasitoids attacked a much higher proportion of aphids that did respond but oviposition success on this group was poor. The number of aphid-infested needles on seedlings increased significantly owing to the parasitoid's foraging activity. On the basis of these results, it is suggested that D. leucopterus is only likely to be of benefit in biological control if used in conjunction with other complementary natural enemies.

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“…Hot and dry weather, with 20 to 40 mm of rain per month, has been reported as the optimum for activity and development of the aphid (Miller et al, 1935, cited in Culliney, 1981Barnes et al, 1976;Mailu et al, 1980). Katerere (1982) assumed that stands of P. patula suffer fewer attacks if planted in high rainfall areas while in Hawaii peaks of the aphid population occurred in rainy seasons when the nutritious value of tree sap was considered to be most favourable for the aphid (Culliney, 1981). Carter and Barson (1973) reported that the threshold temperature for flight of the aphid was 16°C in southern England and he assumed that the phenological condition of the host plant was responsible for the fluctuations in the mean date of flight.…”

Section: Life Cyclementioning

confidence: 97%

The Pine Woolly Aphid,Pineus pini(L.)—A Pest of Pines in South Africa

Zwoliński

1989

South African Forestry Journal

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Aphid Density and Animal Damage to Pinus patula Schiede and Deppe in a Clone Bank at Melsetter Forest Research Station

Cited by 5 publications

References 3 publications

Biology and Population Dynamics of the Pine Needle Aphid, Eulachnus rileyi (Williams) in Zimbabwe

Biology and Population Dynamics of the Pine Needle Aphid, Eulachnus rileyi (Williams) in Zimbabwe

Population dynamics and foraging behaviour ofDiaeretus leucopterus(Hymenoptera: Braconidae), and its potential for the biological control of pine damagingEulachnusspp. (Homoptera: Aphididae)

The Pine Woolly Aphid,Pineus pini(L.)—A Pest of Pines in South Africa

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